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Invalid Narrow Pitch Threshold message for Engine Speed Channels

MoTeC M1 Software Tutorial

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I'm setting up my M150 in my Honda (H series engine) to prepare for dyno tuning. I have successfully set up all of the sensors and other items, and the M150 achieves cycle lock quickly. I've managed to get the car to start and idle reasonably well. I thought I was ready to start refining the idle fuel and timing settings, but I noticed that I'm getting an "Invalid Narrow Pitch Threshold" message on the Ref/Sync worksheet.

A screenshot is attached. The trigger wheel is a custom 24-1 setup on the crankshaft with a cam sensor for the sync. It ran successfully on my former M400, so I know the hardware should be good. I did not alter the narrow or wide pitch thresholds from the default settings, so I figure there is some other setting I need to adjust. I would appreciate any suggestions, as web searching did not yield many results.

Attached Files

Quick update - I figured I'd try some other settings. Changing the Narrow Pitch Threshold to 60% resolved the fault I honestly don't know why - so I'd like to get a better understanding of this setting and how changing from 50% to 60% fixed the fault when the documentation (and the course) stated that for the vast majority of engines, the default setting of 50% should work.


Look at the help for Engine Speed Reference Narrow Pitch Threshold. The help explains the parameter very well, and you can understand why a tooth wheel with fewer teeth (like a 24 tooth instead of 36 or 60) would more easily have the fault. particularly with an engine with only 4 cylinders. There is also a recommended procedure to determine this value by cranking and analyzing the data.

To visualize this, use the Online->Capture Inputs... particularly when cranking.

BTW -- from the help, the recommendation is to use 60%, so I think this is really a non issue.

Thanks for the reply David. I just discovered those help pop ups. I was trying to search the M1 Tune User Manual.

With M1 Tune, the F1 Key is your friend.

Depending on where the missed tooth gap falls, it may have been that there was another point in the engine cycle that slowed the crank enough that the gap between the normal teeth widened enough that it exceeded the 50% threshold for the detection of the tooth gap, leading to the M1 trying to recognise this as the gap. Setting the Narrow Pitch threshold higher makes allowances for this variance in instantaneous Engine Speed. If you do an Input Capture with no spark plugs, and one with only Cylinder 0 installed, then you can see how the rotational speed changes with compression.

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